This invention relates generally to semiconductors, and more specifically, to semiconductor structures having an air gap.
By significantly reducing the spacing between conductive metal lines in semiconductors, a decrease in capacitive coupling is needed. This decrease in capacitive coupling causes less cross-talk, lower capacitive losses and decreased RC (resistor/capacitor) time constants. In order to reduce capacitive coupling, much effort has been directed toward developing low dielectric constant (low-k) materials to replace conventional dielectric materials that are interposed between the metal lines. The lowest possible dielectric constant is 1.0 but most manufacturable materials typically have a dielectric constant of at least 2.5 or greater. Air has a dielectric constant of 1.0 and does not have the cost associated with many materials having a dielectric constant that is not as low as air. There have been attempts to fabricate semiconductor devices with air gaps between metal leads to reduce the capacitive coupling between electrically conducting members. Known semiconductor structures having air gaps are of varying complexity. Generally, an area within a semiconductor is identified for placement of an air gap. A layer is formed and a portion of the layer is etched in the identified area to form a cavity around which the air gap is created. The air regions are sealed, enclosed or isolated by a deposition technique.